An American and a Russian spaceflier are in good shape after they were forced to abort their trip to the International Space Station due to a rocket anomaly, but today’s scary launch has cast a pall over orbital operations going forward.

NASA astronaut Nick Hague and Russian cosmonaut Alexey Ovchinin were due to begin a six-month stint in orbit with their launch from Russia’s Baikonur Cosmodrome in Kazakhstan, aboard a Soyuz spacecraft that was perched atop Russia’s workhorse Soyuz-FG rocket.

Just minutes after liftoff at 2:40 p.m. local time (1:40 a.m. PT), the rocket booster experienced an anomaly, and the ascent was aborted. Video showed the booster breaking up at high altitude.

The Soyuz spacecraft was thrown clear of the rocket and plunged back to Earth for a ballistic landing, with peak acceleration estimated at 6 to 7 G’s. After a nail-biting interval, a search and rescue team located the craft and retrieved Hague and Ovchinin in good condition.

NASA said the pair would be flown back to Russia’s Star City cosmonaut center, outside Moscow, for further examination and debriefing.

“Safety of the crew is the utmost priority for NASA,” the space agency said in a statement. “A thorough investigation into the cause of the incident will be conducted.”

NASA Administrator Jim Bridenstine, who has been visiting Russia and Kazakhstan in conjunction with today’s launch, said he was “grateful that everyone is safe.”

Russia’s space agency tweeted out pictures of the spacefliers sitting in a lounge in Kazakhstan after their retrieval from the Soyuz capsule:

Crewed flights to the space station will be suspended while the investigation unfolds, and that’s likely to scramble the schedule of the station’s comings and goings. Russia’s Soyuz craft currently provides the only means to get to and from the orbital outpost. Two breeds of U.S.-built space taxis are being developed by SpaceX and Boeing, but the current schedule doesn’t call for them to carry astronauts until next June at the earliest.

Three spacefliers — NASA’s Serena Auñón-Chancellor, Russia’s Sergey Prokopyev and Germany’s Alexander Gerst — are currently aboard the station. They’re scheduled to ride a Soyuz that’s docked to the station back down to Kazakhstan in December, but that departure date may now be up for discussion.

If Soyuz launches are suspended for an extended period, one of the potential options would be to let the current crew return as planned and leave the station temporarily uncrewed. Such a scenario was considered in 2011 when one of Russia’s robotic Progress cargo ships was lost due to a rocket malfunction, forcing an investigation. In that case, Russian investigators gave the Soyuz a clean bill of health soon enough that mission managers could avoid having to go with the crewless option.

Today’s anomaly comes on top of an earlier setback for the space station program, involving an air leak in the Soyuz that’s currently docked to the station. The crew was able to track down the leak and patch up a small hole in the spacecraft’s hull, but the investigation of the cause is continuing. Speculation over whether the hole was made accidentally or intentionally has been a source of consternation for the long-running U.S.-Russian space relationship.

Here are some of the reactions and ruminations that broke out on Twitter after today’s abort:

Russian sources report the Soyuz failure occurred about 2 minutes into the launch. There are rumors one of the strap-on boosters had a problem and impacted the launch during the time of second stage separation. Again, this is all unconfirmed.

— Eric Berger (@SciGuySpace) October 11, 2018

Soyuz MS-10 failure, crew safe. My take based on watching launch coverage replay: At 1st stage separation, there was structural damage to the core stage and shortly thereafter, the crew was ordered to initiate an abort in ballistic mode using the "RUS" hand controller. #NASA #ISS pic.twitter.com/KIZ9iddk5i

— Leroy Chiao (@AstroDude) October 11, 2018

We're very thankful that the crew members on this morning's #Soyuz launch are safe. We will be reaching out to customers shortly as we learn further information on launch schedule and crew time impacts. We're having ongoing discussions with our friends at @NASA. #ISS

— NanoRacks (@NanoRacks) October 11, 2018

The last #Soyuz down-range abort was on April 5, 1975. The crew ended up in the snow in Siberia with wolves pawing at the capsule. They were rescued the next day. First launched in 1966, Soyuz rockets are by far the most veteran launch vehicles on the planet. 1700 launches.

— Miles O'Brien (@milesobrien) October 11, 2018

Because of the Soyuz launch failure today there will only be one soyuz docked at the iss. The Soyuz module has a lifespan of 215 days due to fuel tank degradation. They usually land them just after 200 days. The current soyuz docked to the iss will hit 200 days in December.

— Taco Squirrel (@squirrel_taco) October 11, 2018

Really can be interesting to watch some of the more experienced NASA Houston guys (shall we say) explaining what they thought happened with the Soyuz. This guy is very expressive right now! pic.twitter.com/blS89PGXWG